In the following query, if the LEFT keyword is replaced with the RIGHT keyword, the total number of rows that are returned must equal:

SELECT
vendor_name,
invoice_number
FROM
invoices
LEFT JOIN
vendors
ON
invoices.vendor_id = vendors.vendor_id

a) the number of rows in the Invoices table
b) the number of rows in the Vendors table
c) the number of rows in the Invoices table plus the number of rows in the Vendors table
d) none of the above